36results about How to "Reduce current harmonic content" patented technology

The present invention provides a single-phase five-level topology and an inverter. The single-phase five-level topology includes: a first capacitor, a three-level bridge arm module and four switch tubes, and the four switch tubes are respectively the first switch tubes , the fifth switch tube, the sixth switch tube and the eighth switch tube; each switch tube is connected in reverse parallel with a diode; the three-level bridge arm module includes two switch tubes and a double switch unit, and the first switch tube of the third switch tube terminal connected to the first node, the second end of the third switch tube is connected to the neutral point N through the double switch unit; the first end of the fourth switch tube is connected to N through the double switch unit, and the second end of the fourth switch tube is connected to the first node Two nodes. Output five level states, reduce the current harmonic content of the system, reduce the filter inductance, increase the voltage level, suppress the common mode voltage, and improve the operating efficiency. The balance control of the capacitor voltage under full power and full modulation can be realized without adding additional hardware circuits, and the phase output voltage of the system can be prevented from degrading from five-level to three-level.

The invention discloses a double-coil connected medium-voltage power feed system and a power feed method for an urban rail power supply system. The system includes a rectifier transformer, a double-coil connected power feed device and a rectifier unit. The type energy feed device comprises two double energy feed branches arranged in parallel, and each heavy energy feed branch includes an AC-side low-voltage circuit breaker, an isolation transformer, an inverter and a DC-side contactor arranged in series; the method steps include: When starting, the rectifier transformer and rectifier unit take current from the medium-voltage AC power grid and inject it into the DC traction network; Feed back the train braking energy to the medium voltage AC grid. The invention can realize energy saving and DC bus voltage stabilization, and has the advantages of high flexibility, small size, high degree of integration with existing systems, high power factor, low harmonics injected into the AC side, and good versatility.

The invention provides an opening-winding permanent-magnet synchronous motor driving system for mine traction and a working method thereof. The driving system is composed of a first power supply circuit connected with a three-phase voltage, a second power supply circuit connected with the three-phase voltage, a permanent-magnet motor connected with the first power supply circuit and the second power supply circuit, a sampling module connected with the permanent-magnet motor, a main control module connected with the sampling module, and a driving module connected with the main control module, the first power supply circuit and the second power supply circuit. The driving system has the following beneficial effects: the neutral point of the permanent-magnet synchronous motor is opened to form a winding opening structure with dual ports; the opening-winding permanent-magnet synchronous motor is used as a driving motor of the mining electric locomotive, so that the requirement of the largestarting torque is met and the starting characteristic of the driving system is improved; and two converters are connected to the two ends of the opening-winding permanent-magnet synchronous motor, so that the system stability is improved and the fault rate is reduced.

The invention discloses a three-phase three-level high-frequency link matrix rectifier topology and a modulation method thereof, and relates to the field of topology and modulation of electronic powerinverters. The three-phase three-level high-frequency link matrix rectifier topology comprises a three-phase three-level matrix inverter of which the input terminal is electrically connected with a power network and the output terminal is electrically connected with the primary side of a transformer; each phase of the three-phase three-level matrix inverter comprises four groups of two-way switchunits that are common-emitter series-opposition structures; and the three-phase three-level matrix inverter is also provided with a three-level structure in which a neutral point clamped diode and aneutral point clamped capacitor are replaced with two-way switch units respectively. From the view of circuit topology, the three-phase three-level high-frequency link matrix rectifier topology has advantages of large output capacity, high output voltage, low current harmonic content and the like by introducing more switch tubes. By adopting the decoupled and coupled dual-carrier SPWM modulation method, the voltage-withstanding level of components is beneficially reduced, the unit power factor in the grid side is realized, and the content of low-order harmonics of the input current is reduced.

The invention discloses a concentrated direct-current power supply skid-mounted electric automobile charging device. A solid insulating ring network cabinet is arranged in a high-voltage chamber; a dry transformer is arranged in a transformer chamber; a low-voltage switch cabinet, a monitoring cabinet, an AFE (analog front end) and a charger are arranged in a low-voltage distribution chamber; a hoisting hanging point is formed at the bottom of a charging house; a grounding copper bar is arranged at the bottom of the charging house; an air-conditioning outdoor unit chamber is arranged above the transformer chamber and used for assembling an air-conditioning outdoor unit; and the outer wall of the charging house is provided with wire inlet and outlet holes. The device has the advantages of concentrated rectification, dispersed direct-current power supply, direct supply of direct-current power supply to multiple chargers after the alternating current is converted into direct current by adopting rectification of the AFE, high power factor, low current harmonic content, no influence on power quality of a power grid, capability of directly connecting the electrical energy generated by new energy generating equipment of solar energy, wind energy and the like to a direct-current bus, small volume and high protection level due to the use of a skid-mounted house body, integral field assembly, convenience for transportation, and waterproof, fireproof and wind-sand resistant properties of the house body.